Automatic test equipment such as, for example, that used for testing avionics systems, requires internally generated stimuli corresponding to particular parameters to be tested, and further requires that the generated stimuli be measured to determine their accuracy. Additionally, it is desirable that the test equipment have the capability of measuring externally generated signals corresponding to the particular parameters.
Servo systems using stepper motors such as chart visual indicator systems require test equipment with this capability. Additionally, the test equipment needs the capability to function as part of the servo system, wherein the stimuli generated by the test equipment is a function of some measurement of the externally generated signals.
Prior to the present invention, equipment of the type described has had the disadvantages of being somewhat cumbersome and inflexible, and required complicated circuitry dedicated to a particular servo system.
Accordingly, the main object of this invention is to overcome the aforenoted disadvantages by providing equipment including digital and analog components for closed loop control of stepper motors used in servo systems via computer interfacing, thereby allowing parameters such as motor speed and/or position to be specified by the computer.
Another object of the invention is to allow manual control of the stepper motors via a slew stick arrangement.
Yet another object of the invention is to achieve a desirable versatility in that a plurality of independently controlled simultaneously operated stepper motors can be accommodated.